function Cat(name, color) {
    this.name = name; // this指向它的实例
    this.color = color;
}
var cat1 = new Cat("大毛", "黄色");
var cat2 = new Cat("二毛", "黑色");

console.log(cat1.constructor == cat2.constructor); //构造函数
console.log(cat1 instanceof Cat);
console.log(cat2 instanceof Cat);